A Model of the Flickermeter for Frequency Modulation of the Input Voltage

Flickermeter is a term used for a system that measures the obnoxiousness of flicker caused by voltage fluctuations. The processing performed by a signal chain of this system is very complicated. Thus, it is not easy to obtain the output values only by analytical mean. The aim of this paper is to obtain a simple model of a flickermeter for a case of frequency modulation (FM) of the input signal. There is still a lack of a International Electrotechnical Commission flickermeter standard specification for that case. In this paper, a proposal was made to determine such a model at FM with slowly varying signals and signals in a frequency range from 1 Hz to 155 Hz. The quality of characteristic approximation evaluated was based on numerical simulations with sinusoidal as well as rectangular waveforms as input signals. The presented model makes it possible to clearly understand the flickermeter signal chain operation and helps to verify the functioning of a real measuring device in the considered frequency range.

I. Introduction

The POWER network's voltage quality could be evaluated, among others, by the analysis of the voltage fluctuations. In practice, two measures of the voltage fluctuations are being used, i.e., short-term and long-term flicker severity indicators [1], [2] and voltage fluctuation indexes [3], [4]. Standard and indicators help to evaluate a flicker [5] obnoxiousness caused by the power network's voltage fluctuations. The values for indicators are obtained with a measuring system called the flickermeter. Flicker sensing is a very complex process. Each component block of a flickermeter system emulates the processes in a chain consisting of the light source–eye–brain. The processing performed by this chain is complicated to such extent that it is rather difficult to obtain the output values only in an analytical way. The flickermeter is standardized for two nominal frequency values, i.e., 50 Hz and 60 Hz. The analysis, whose results are presented here, has been made with 50 Hz nominal frequency. The standard characteristics of flickermeter processing [2] are based on a given set of standard points described by the modulation depth and frequency at a given waveform of the modulating signal. Thus, the standard specification only refers to amplitude modulation (AM) with sinusoidal and rectangular modulating signals [2]. However, in the subject literature, the AM, e.g., [6]–[14], and the voltage phase modulation (PM), e.g., [15]–[17], are considered.